Friday, February 10, 2012

Pushed over the quantum edge

Besides Gil and Robert Alicki, other notable QC skeptics include Leonid Levin (of Cook-Levin Theorem fame), Oded Goldreich, Gerard ‘t Hooft (the Nobel physicist), Stephen Wolfram, and Ed Fredkin (well, he actually believes P=BQP). Besides them, my experience has been that there’s also a significantly larger group of physicists, chemists, and computer scientists who agree with the anti-QC sentiments but haven’t articulated them in print (there were even a few who angrily accosted me after department colloquia to accuse me of peddling lies!) If you read the comment threads on Gil’s blog, you’ll see lots of contributions from two more skeptics, both of whom played large roles in “pushing me over the edge” to make this bet: Roger Schlafly (author of a book called “How Einstein Ruined Physics”) and Craig Feinstein (author of numerous wrong P!=NP proofs).

So a lot of important scientists are skeptical about quantum computing (see also here), and they do not necessarily say so on the record. But a few negative blog comments, and he goes ballistic!

Craig criticized it in comments here, and I did on this blog and here.

Quantum computing is one of those subjects that academic scientists are not supposed to criticize because it gets a lot of govt grant funding. It frequently makes extravagent promises about a new computer paradigm, and computers that will outperform all current computers. None of its promises have ever been realized, and there is no likelihood that they ever will. I am glad that I have provoked Scott into defending his position, but his offer is meaningless because he has defined it in a way so that he will never have to pay.

Scott is entitled to his opinion, of course. But we ought to understand that he is doing abstract analyses of hypothetical computers that do not exist in the real world, and are probably contrary to the laws of physics.

I study quantum computing at MIT. Recently, on my blog, I offered a $100 000 reward for a demonstration, convincing to me, that scalable quantum computing is impossible in the physical world. The award is entirely at my discretion; ...

Most of the skeptics say that they have no problem with quantum mechanics itself (it is, after all, the best-confirmed physical theory of all time); it's only scalable quantum computers that they object to. To date, though, no one really knows how you can have quantum mechanics without the possibility of quantum fault-tolerance. So as I see it, the burden falls on the skeptics to give an alternative account of what's going on that would predict the impossibility of scalable QC.

I think that is a strange view. Quantum mechanics is the best explanation we have of what is going on. It just does not imply scalable QC, and all attempts at scalable QC have failed.